Electric discharge apparatus



21, 195 H. w. VAN NEss 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952' 17 Sheets-Sheet l I\1I/ELDER Fig. IB. POWER SUPPLY UNIT Figs. 16, lD,c|nd IE.

SEQUENCE TIMER V COUPLING UNIT Fig.|F. Figs. IG,IH,ond II.

POLARITY SELECTOR F "3- I FREQUENCY AND HEAT CONTROL UNIT Fig IJ.

PULSE COUNTING UNIT WITNESSES: INVENTOR F lg. IA

Hubert W. Van Ness.

ATTORNEY Aug. 21, 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 1 Sheet-Sheet 2 WELDER VPR I sv I El I M I E I I I I I L3, I MRXB L2, I me Li, I MR) i I I I/'r| I I ALI I AL2 l I l i l M3 I WITNESSES: INVENTOR Hubert W. VanNess.

ATTORNEY 21, 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 Sheets-Sheet 3 ALaALQ

AL8) AL9) WITNESSES: g '0 INVENTOR dww/z Hubert W. Van Ness aim ATTORNEY Aug. 21, 1956 H. w. VAN NESS 2,750,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 h h 4 POWER SUPPLYUNIT ALB WITNESSES: Fig ID INVENTOR 5.477% Hubert W.Von Ness.

ATTORNEY Aug. 1, 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 I 17' Sheets-Sheet 5ALB/ WITNESSES: INVENTOR ATTORNEY Fig.iE 4 t K Hubert W. VonNess. 9/ BYAug. 21, 1956 H. W. VAN NESS ELECTRIC DISCHARGE APPARATUS 17Sheets-Sheet 6 Filed June 4, 1952 Non-Repeat INVENTOR Huber? W. VanNess.

ATTORNEY WITNESSES: Q ENCE T1MER Fig. IF. $5M j. J

Aug. 21, 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 Sheets-Sheet '7 2T06ITOS T05 |TO5 5806 IISO6 9506 2505 8505 2PO6 IP06 2PO5 IP05 I SLI v l rI s| 2,

2583 I s 3 SP3 Fig. IG. WITNESSES: INVENTOR HuberT W. Van Ness.

BY 6W {50m (9 ATTORNEY Aug. 21, 1956 H. w. VAN NESS 2,750,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 Sheets-Sheet 8COUPLING UNIT 2T04 l T04 2TO3 n03 I504 9503 IOSOB s| 2P04 IP04 2P03 IP03I $1.2 l

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WITNESSES: INVENTOR ,4 W Hubert w, VunNess.

f g az a ATTORN EY 1, 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 Sheets-Sheet l0 POSTHEAT UNIT POLARITY SELECTOR UNIT PULSE 0| coumme I UNlT WITNESSES: IINVENTOR 9,4 j b-2 Hubert W. Van Ness.

I, w S L M ATTORN EY H. W. VAN NESS ELECTRIC DISCHARGE APPARATUS Aug.21, 1956 17 Sheets-Sheet ll Filed June 4, 1952 I. 06 I 5 m u mm! 6,228+R O T N E V Q Q fly m V W/ m5 6.223 2 2 m N? 3: 5":

WITNESSES: %z%z Huber? W. Van Ness.

ATTORN EY Aug. 21, 1956 Filed June 4, 1952 H. W. VAN NESS ELECTRICDISCHARGE APPARATUS 17 Sheets-Sheet 15 Hubert W. Van Ness.

ATTORN EY 1. 1956 H. w. VAN NESS 2,760,141

ELECTRIC DISCHARGE APPARATUS Filed June 4, 1952 17 Sheets-Sheet l6 ALIAL2 FREQUENCY AND HEAT CONTROL UNIT Post Heat ,DLl'

ALs I79 04 RH m' BL}; :I I54 W CF 5455 I73 RF 1' n2 M57 ,ALI

WITNESSES: INVENTOR Hu beri Van Ness.

ATTORNEY Aug. 21, 1956 H. w. VAN NESS ELECTRIC DISCHARGE APPARATUS 17Sheets-Sheet 17 Filed June 4, 1952 30 20 3&4

NELB N4 3 2m mm. 6 E5 0 INVENTOR Hubert W. VonNess BY 6 ATTORNEY mom rSm$5.655; 33 22 r 3.5333... 95.2w 2 .3 :PzEE m;

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United States Patent ELECTRIC DISCHARGEAPPARATUS Hubert W. Van Ness,Bulfalo, N. Y., assignor to Westinghouse Electric Corporation, EastPi'ttsburgh, Pa., a corporation of Pennsylvania ApplicationJune 4,1952,.Serial'No. 291,598.

12 Claims. (Cl. 321-7.)

and me, and both assigned to Westinghouse Electric Corporation.

The above-described applications relate to-control'apparatus forpolyphase to single phase low-frequency welders in which the power forwelding is derived through electric discharge valves interposed betweena polyphase supply and the primary of a welding transformer; In theapparatus disclosed in the earlier application, the reversal of the loadcurrent is effected by operation ofmechanical reversing contactors; inthat disclosed in the l-ate'rapplication, the reversal is eilected bymeans of mechanical relays. The apparatus disclosed in theseapplications is highly satisfactory for most of the welding applicationswhich arise. However, to expand the usefulness of welding to meet theever-increasing needs of industry, it is desirable that very high-speed,highly flexible welding apparatus be provided. The mechanical contactorsand relays of the apparatus disclosed in the above-describedapplications militate to an extent against this literally unlimitedexpansion of the use of welding.

It is, accordingly, an object of my invention to provide highlyflexible, very high-speed welding apparatus.

It is also an object of my invention to provide control apparatus for apolyphase to single phase low=frequency Welder which uses electronicinstead of mechanical switching components.

It is another object of my invention toprovide a polyphase to singlephase low-frequency welding system, the control of which uses electronicinstead of mechanical switching components.

In accordance with my invention, I provide control apparatus whichincludes electronic components, such as thyratrons and high-vacuumtubes, in places Where relays are ordinarily used in accordance withthe-teachings of the prior art or of the above-entitled applications.Because of the complexity of the operation which is to be carried out ina polyphase to single phasel'owfrequency welder, an electronic system ofthis type is inherently highly complex. To reduce initial costs and thecosts of installing and maintaining the apparatus, it is desirable thatthe complexity be reduced to the extent practicable.

It is, accordingly, a specific object of my invention to provideelectronic control apparatus for a polyphaseto single phaselow-frequency welder of the simplest practicable construction.

The apparatus in accordance with my invention in- 2,760,l4l PatentedAug. 21,, 1%56 This unit may be regarded as a converter which transmitspower between a plurality of power supply conductors or buses adapted tobe connected to a polyphase source, and a pair of load conductors orbuses which are connected to the two terminals of the single primary ofa welding transformer. In one embodiment of my invention, four groups ofelectric discharge devices such as ignitrons are provided. Each of thesedevices has an anode, a cathode and an igniter of other controlelectrode. The anode of one ignitron of each of the first group isconnected to asupply conductor and the cathode to one of the loadconductors; the anode of each ignitron of the second group is connectedto a different power supply conductor and the cathode to the other loadconductor; the cathode of each ignitron of the third group is connectedto a difiierent power supply conductor and the anode to the firstmentioned load conductor; the cathode of each ignitron of the fourthgroup is connected to a different power supply conductor and the anodeto the other load conductor. Each of the ignitrons is controlled from athyratron connected to conduct current through its igniter and thethyratrons are controlled from a heat control. circuit. The ignitronsare so connected that those of. the first and fourth groups, whenrendered conductive, conduct current of one polarity through theprimary, and those of the second and third groups, when renderedconductive, conduct current of the opposite polarity.

As will be realized from even a cursory consideration of'the apparatusdisclosed in the above-described applications, the heat-control portionof this apparatus is relatively complex. In providing the electronicapparatus, it is desirable that the heat-control apparatus besimplified.

It is, accordingly, also an object of my invention to provide aheat-control circuit of comparatively simple structure for a polyphaseto single phase low-frequency welder.

In accordance with my invention, I provide a heatcontrol circuitincluding a coupling unit having connected thereto a network of simplestructure for producing the heat control. The coupling unit includes aplurality of like circuit units, each unit being connected to fire apair of ignitrons of the. first and fourth groups and a correspondingpair of ignitrons of the second and third group, the two pairs ofignitrons deriving their power from the same two buses of the supply.Each circuit unit includes an auxiliary electric discharge device incircuit with a pair of the branch networks through which the firing ofthe ignitrons is directly effected. One network is connected to fire theassociated ignitrons which conduct current of one polarity, and theother to fire the corresponding ignitrons which conduct current of theopposite polarity. The networks are connected in the anode circuit ofeach auxiliary device through selective electronic switch means so oneor the other network may be selected. Each circuit unit is supplied withpotential in phase with the potential of the phase of the source fromwhich the corresponding ignitrons are supplied. This potential isimpressed in the principal circuit of the auxiliary discharge device ofthe unit. In the control circuit of each auxiliary discharge device, apotential lagging the principal potential in phase and derived fromanother phase of the source than the one from which the associatedignitrons are supplied is impressed. On this potential, a pulsatingdirect-current potential is superimposed. The latter potential iscontrolled in accordance with the desired characteristics of the weldingcurrent. It may be set to provide firing at any angle in the periods ofthe supply and thus to achieve any desired heat control. The couplingunit with its associatedpulsating direct-current supply, and the switchmeans are controlled from a sequence timer through a frequency controlcircuit. The control is such thatat the will of an operator,

ice

currents of opposite polarity may be transmitted alternately through theprimary of the welding transformer through the first and fourth andsecond and third groups of ignitrons, or currents of either polarity maybe transmitted through the first and fourth or second and third.

It is desirable in the interest of flexibility that during each weldingoperation a preselected number of lowfrequency impulses be supplied.

It is, accordingly, a further object of my invention to provide controlapparatus for a welding system having facilities for determining thenumber of impulses of lowfrequency current to be supplied for welding.

A further ancillary object of my invention is to provide a noveltime-constant network.

A further ancillary object of my invention is to provide a novel timingcircuit.

In accordance with my invention, these latter three objects areaccomplished with a novel sequence timer including a circuit fordischarging the capacitor which times the duration of the weldingcurrent, progressively in steps, the number of which may be determinedat will. The discharging circuit is in this timer provided with anelectric discharge device which is repeatedly turned on after eachwelding pulse.

In carrying out my invention, I have found that by introducing so-calledflip-flop circuits in the proper places in the apparatus, the circuitsfor attaining many of the functions of the equipment are materiallysimplified. A flipflop circuit is defined as a circuit usually includinga pair of electric discharge devices, having a first condition in whichone of the devices is conductive and prevents the other from beingconductive, and a second condition in which the latter device isconductive and prevents the former from being conductive and which iscapable of passing abruptly from one of these conditions to the otherwhen a signal is impressed thereon. The electronic switch whichselectively connects one or the other of the networks in the circuitunits of the coupling unit is, according to my invention, operated by aflip-flop circuit. The direct current impressed in the control circuitsof the auxiliary thyratrons in the circuit units to determine the heatcontrol at which the power supply unit operates, is varied by twoflip-flop circuits in accordance with my invention. A further flip-flopcircuit cooperates with the sequence timer to determine the duration andcharacter of the welding pulses.

It is an ancillary object of my invention to provide a novel flip-flopcircuit particularly suitable for electronic control apparatus for apolyphase to single phase lowfrequency welder.

By combining the novel power supply unit, as described above, with thenovel heat-control circuit, the sequence timer, and the variousflip-flop circuits, I have provided electronic control apparatus for apolyphase low-frequency welder. This control apparatus is highlyflexible and is capable of operating at a high speed and of deliveringpulses for welding of one polarity, alternately of one polarity and theopposite polarity, or of alternating polarities.

The features of my invention which I consider novel are set forthgenerally above. The invention itself, however, both as to itsorganization and its method of operation, together with additionalobjects and advantages thereof, will be understood from the followingspecific embodiment when read in connection with the accompanyingdrawings, in which:

Figure 1A is a block diagram of a preferred embodiment of my invention;

Figs. IE to 1K together constitute a circuit diagram of my invention;

Figs. 2A and 2B together constitute a graph illustrating the operationof the heat-control circuit in accordance with my invention; and

Figs. 3A and 3B and 4A and 4B together each constitutes graphs showingthe various voltages and currents which flow during two sequences ofoperation in accordance with my invention.

Figs. 5 and 6 show modifications of details of the disclosed circuit.

Description of Figs. 1A to 1K The welding system shown in Figs. 1A to 1Kconsists of a Welder, a Power Supply Unit, a Coupling Unit, a PolaritySelector Unit, a Frequency and Heat-Control Unit, a Post-Heat Unit, aSequence Timer and a Pulse- Counting Unit. Power for the system isderived from the buses or conductors L1, L2, L3 of a commercialthreephase source in which are connected three reactances RXl, RX2 andRX3, which absorb the effect of short circuits or commutationfluctuations of the type described in application Serial No. 272,818.These reactances may be lumped, or they may be the available regulationof the supply.

The power for welding is derived directly from these main buses L1, L2,L3. Alternating-current power for certain of the control components isderived from auxiliary buses AL1 and AL2, which are energized from thebuses L1 and L2 through a transformer T1. Certain of the components ofthe system are energized from direct current derived from auxiliarybuses AL3, AL4, ALS, AL6 and AL7. These buses are shown as connectedacross batteries B1, B2, and B3 (Figs. 11 and 1K). These batteries aresymbolical of direct-current sources of any convenient type, which inthe practice of my invention are usually rectifiers, connected to two ofthe buses of the supply and including suitable filters. Of the busesAL3, AL4, ALS, AL3 is most positive and ALS most negative; of the otherbuses, AL6 is more positive than AL 7. Bus AL3 and alternating-currentbus AL2 are at the same potential.

The Welder includes a welding transformer W having a single primary Pand a secondary S, a pair of welding electrodes E1 and E2 connected toS, one of which, E1, is movable by a hydraulic cylinder C in and out ofengagement with material M to be welded, a magnetically actuable valve Vwhich controls the admission of fluid under pressure into the cylinder,and a pressure switch PS operated by a pressure relay PR which closeswhen adequate pressure is applied by the electrodes to the material M.Each of the windings P and S of the transformer W may be made up of anumber of subwiudings connected either in series or in parallel. Thesolenoid SV for the valve V is controlled from a starting relay SRhaving normally open contacts 19 and 21.

The Power Supply Unit includes a plurality of ignitrons I-1, I-2, 1-3,1-4, 1-5, I-6, 1-7, I-S, I-9, 1-10, I-11, and 1-12. Each ignitronincludes an anode 23, a cathode 25, and an igniter 27. These ignitronsmay be divided into four groups which are connected between the supplybuses L1, L2, and L3 and load buses AL8 and A129. the latter being inturn connected to the terminals of the primary P.

The ignitrons of the first group are 1-1, 1-2 and I-3, and their anodes23 are connected each to a supply bus L1, L2 and L3, respectively, whiletheir cathodes are connected to the load bus AL9. The ignitrons of thefourth group are 1-4, 1-5 and 1-6. The cathodes 25 of these ignitronsare connected to the buses L1, L2, and L3, respectively, while theiranodes are connected to the load bus ALS. It is seen that the ignitrons1-1 to 1-3 and I-4 to 1-6 are so connected that current may be conductedupward through the primary P and through pairs of these ignitrons onefrom each group. Thus, when bus L1 is positive relative to L2, theconduction is through ignitrons 1-1 and I-S. Depending on therelationship between the potential of the buses L1, L2 and L3, the otherignitrons conduct.

The second group of ignitrons are I-7, 1-8 and 1-9. The anodes 23 of thelatter are connected each to a bus L1, L2, L3, respectively, and thecathodes 25 are connected to the load bus ALS. The third group isignitrons I-10, I 1 1 and I-12, and their cathodes 25 are connectedtothe buses L1, L2 and L3, and their anodes 23to' the load bus AL9. Theignitrons I-7 to P9, and I-10 to I-12, may thus conduct current'downwardly through the primary P in pairs, one ignitrons from eachgroup.

Each of the ignitrons I-l to I-"-12 is provided with a firing thyratronFT1 to FT12. Each firing thyratron has an anode 29, a cathode 31 and agrid 33; Each anode 29 is connected directly to the anode 23 of thecorresponding ignitron and the cathode 31 through a load resistor 35,37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57 to the corresponding igniter27. Each grid 33'is'connected through a grid resistor 59, 61, 63, 65-,67, 69, 71, 73, 75, 77, 79, 81, and a pair of input resistors 83' and85', 87 and 89, 91 and 93, 95 and 97', 99=and 101 I03 and 105, 107 and109, 111 and 113, 115 and 117, 119 and 121, 123 and 125, 127' and 129toa biasing supply 100, 102, 104, 106, 108, 110, 112, 114, 116, 118,-120; 122. Potential to fire the thyratrons F-Tl to FT12 are impressedacross the resistors 83 to 129 from the Goupling Unit.

The Coupling Unit includes a plurality. of like circuit units eachassociated with a pair of ignitrons of the first and fourth group and apair of ignitrons of the second and third groups of the Power SupplyUnit. The pairs with which each circuit unit is associated are thosewhich conduct simultaneously. Each unit includes a thyratron GT1 GT2,GT3, GT4, GT and GT6, each thyratron having an anode 130, a cathode 131,and a grid'132. The circuit units are supplied and controlled in pairsGT1-GT2, GT3CT4, GT5-GT6.

The unit including thyratrons GT1 and GT2 are supplied from atransformer ST1, the primary SP1 of which is connected between the busesL1 and L2.. These units control ignitrons-I-l and'l 5, I-7 and I11', I-2and I-4, and L8 and I-10, respectively, which are connected to the samebuses L1 and L2. Thesupply potential for the units GT1 and GT2 is thusin phase with the supply potential for the associated ignitrons.Similarly, the circuit units including the ignitrons GT3 and GT4 aresupplied from transformer ST2, the primary SP2 of which is connectedacross the buses L1 and LS. These units control associated ignitronsconnected to the same buses. The units including the thyratronsGTS andGT6 are controlled from a supply transformer ST3, the primary of whichis connected between the buses L2 and L3. These units are related toassociated ignitrons in the same manner as the other unit.

Each supply transformer ST1, ST2 and ST3 is provided with a pair ofsecondarieslSSl, 2551, 1882, 2882, 1833, 2853, the supply secondaries1SS1 and 2SS1, 1582 and 2582 and 1883 and 2583 of units supplied fromthe same supply transformers being oppositely wound so that thepotentials derivable from these secondaries are in opposite phase. Thus,the potential derivable from the secondary 1881 is in opposite phase tothe potential derivable from the secondary 2581.

Each circuit unit is provided with a pair of output transformers 1TO1and 2TO1, 1TO2 and 2TO2, 1T03 and 2TC-3, 1T04 and 2T04, 1T05 and 2T05,1TO6 and 2T06. The primaries IP01 and 2P01, IP02 and 2102, 1103 and2103, 1P04 and 2P04, IP05 and 2P05, and 1206 and 2P06, of thetransformers associated witheach unit are connected together at oneterinitial. The other terminals of one group of primaries 1P01, 1P02,IP03, IP04, 1P05 and IP06 are connected to a switching conductor or busSL1 and the remaining terminals of the other primaries 2PO1, 2102, 2903,21 04, ZPOS, 2P06 are connected to another switching conductor or busSL2. The secondaries of the transformers 1TO1 to 1TO6 and 2T01 to 2TO6are connected across the resistors 83 to 129. in the control circuits ofthe firing thyratrons FTl to FT12 of associ ated ignitrons-l-1 to 1 12.Thus, the secondary 1801 of transformer 2101 is counectedacross theresistor 85 'in the controlcircuit'of firing thyratron FPl; similarly,the sec- 'ondary 5801' is=connectedacross the resistor 101 in thecontrol circuit of the firing thyratron FTS; the secondaries 2S02'and4S02 are "similarly connected to thefiring thyratrons FTZ'and FT4; thesecondaries 4803 and 3503' to firing thyratrons FT4 and FT3; thesecondaries 1804 and 6804 to firing thyratrons PTll and FT; thesecondaries 2S05 and 6s0'5 to the firing thyratrons FT2 and FT6; thesecondaries 3S06 and'5S06 to the firing thyratrons FT3 and'FT6;theseeondaries-7S01 and 11S01 to the firing thyratrons FT7 and FT11, thesecondaries 8802 and 111502 tothe firingthyratrons FTS and FT10; thesecondaries 9503' and 10803 tothe firing thyratrons FT9and'FTlfl;the'secondaries 7S04 and 12S04 to the firing thyratrons FT?and FT 12; the secondaries 8505 and 12305 to the-firing thyratrons FTSand FT12; and the secondaries9S06 and-11806 to the firing thyratrons FT9and FT11. It is to be noted that the identifications of the secondariesof the output transformers above correspond to the. thyratrons in thecontrol circuits of which they are connected, the number at thebeginning of the designation being the same as the number following theletters FT of the associated thyratron.

The units including the thyratrons GT1 to GT5 are completely alike. ineach unit, the secondary of the associated supply transformer 8T1 to 3T3is connected between the junctions of the primaries 1P01 and 2P01' toIP06 and2P06 of the-output transformers and the anode 130 or". thethyratron.- Thus, the secondary 1881 of the first unit is connected tothe anode 130 of the thyratron GT1 and to the junction of the primariesIP01 and 2P01. The primaries thus constitute branch networks in, serieswith the anode of the associated thyratron, and current may flow throughone, IP01, or the other, 2P01, de pending. on Whether current is to beconducted through switching conductor SL1 or switching conductor SL2;The sixth circuit unit includes between the secondary 2SS3 of the supplytransformer SP3 and the junction of the primaries IP06 and 2P06, theprimary P07 of. an additional output transformer T07 and a diode D3, thediode being so connected as to permit current to flow from the anode 130through the primary P07 and either of the primaries 1P06 and 2P06 but toblock the flow ofcurrent of the opposite polarity.

The circuit units are supplied with alternating control potential inpairs GT1, GT2; GT3, GT4; and GT5, GT6 through control transformers KTI,KT2 and KT3, re-. spectively. The primaries K1 1, KP2 and KP3 of thesetransformers are connected to different pairs of" supply buses L1, L2and L3 than the buses to which thecor responding supply transformersST1, ST2 and ST3 are connected. Thus, the primary KP1 is connected tothe buses L3 and L1, while the primary SP1 is connected to the buses L1and L2; the primary KP2 to the buses L2, L3; and the primary SP2 to thebuses L1, L3; and the primary KPli to the buses L1, L2; and the primarySP3 to the buses L2, L3.

The secondaries KS1, KS2 and KS3 of the control transformers are eachprovided with an intermediate tap. The intermediate taps of thesecondaries are connected together to one, DL1, of a pair of conductorsDL1 and DL2 from which controlling direct current is derived: Theterminals of each secondary are connected to the control electrodes 132of the associated thyratrons; thus, the terminals of secondary KS1 areconnected to the control electrodes 132 of the thyratrons GT1 and GT2,and the terminals of the secondaries KS2 and KS3 are simi larlyconnected to the control electrodes of the thyratrons GT3 and GT4 andGT5 and GT6, respectively. The cathodes 131 of all of the thyratrons areconnected to the conductor DL2. Thus, the controlling direct current issuperimposed on the alternating potentials from the. secondaries KS1 toKS3 in the control circuits of, the thyratrons GT1 to GT6. The conductorDL2 is in turn connected to the conductors SL1 or SL2 through switchmeans which is included in the Polarity Selector Unit.

